1. Field of the Invention
The present invention relates to the field of a local area network (designated hereinafter as LAN) and to a unit for assembling electric cables (designated as a xe2x80x9chubxe2x80x9d unit) used in a network LAN. The invention concerns, in particular, a device for switching over hub units, a wiring system including this device, and a method of using this device.
2. Description of Background Information
Recent developments in communications technology such as computer networks have increased the construction of network LAN which connects the terminals of computers or their accessories to one another in rooms or buildings. The network LAN includes a xe2x80x9cpeer-to-peerxe2x80x9d system, as shown in FIG. 1, in which data is exchanged between terminal apparatuses 1 on the same ranking basis. It also includes a xe2x80x9cclient-serverxe2x80x9d system, as shown in FIG. 2, in which a plurality of terminal apparatuses 1 (client apparatuses) are connected to a server 2 which executes administrative functions. In both cases, a hub unit 4 is set up for assembling a plurality of electric cables 3.
The hub unit 4 is a prerequisite for putting into practice a star-type wiring system in network LAN which includes system 10BASE-T. Twisted paired wire cables 3 extend from all terminal apparatuses 1 and control their network.
When hub unit 4 breaks down, a special maintenance staff is needed to repair it. However, during the reparation at least, all terminal apparatuses 1 connected to the broken-down hub unit 4 have to wait for the reparation thereof, before retrieving communications. This causes great inconveniences. Especially, when the specialist is away, the time of waiting for reparation becomes economically unsustainable. Therefore, the specialist is often obliged to be available during all working hours.
Thus, an object of the present invention is to provide a hub unit switching device used in network LAN that secures a communications function. By virtue of this device, when a hub unit breaks down, it can easily be repaired by non-maintenance staff and recovers the communications function.
According to one aspect of the invention, a device is provided for switching over hub units, the device being connected either to a first hub unit or to a second hub unit in an electrically interchangeable manner on the one hand, and adapted to be connected to a plurality of terminal apparatuses on the other hand. The device and the first and second hub units respectively contain an equal number of device ports, first hub ports and second hub ports for entering or emitting data signals. The device for switching over hub units further comprises a unit-conversion switch. The device ports each contain a first, a second, and a third connector. All of the first connectors are connected to the first hub ports via first cables, all of the second connectors are connected to the second hub ports via second cables, and all of the third connectors are adapted to be connected to the terminal apparatuses via third cables. The third connectors each comprise a switching element and are adapted to be switched over either to the first connectors or to the second connectors. The unit-conversion switch controls all of the switching elements, such that the terminal apparatuses can be switched over either to the first hub unit or to the second hub unit.
The device for switching over hub units may comprise a frame, and the unit-conversion switch may be provided outside the frame.
Further, the first, second and third connectors contained in the device ports may be differentiated by colors.
As another aspect of the invention, the unit-conversion switch may be connected in parallel with a remote control device. This remote control device contains a remote control switch, such that all of the third connectors can be switched over either to the first connectors or to the second connectors.
Further, there is provided a wiring system comprising the above-mentioned device and at least one of the plurality of terminal apparatuses connected to the device via the third connectors.
The invention also relates to a method of using the device for switching over hub units, the device being further connected to at least one of the plurality of terminal apparatuses via the third connectors. The method comprises:
electrically connecting at least one of the plurality of terminal apparatuses to the third connectors via the third cables;
electrically connecting the third connectors to the first connectors, so that the device for switching over hub units is connected to the first hub ports via the first cables; and
switching over the unit-conversion switch, when a breakdown occurs in the first hub unit, so that the switching elements are switched over from the first connectors to the second connectors, whereby the device for switching over hub units is electrically connected to the second hub unit, and the first hub unit is thus made ready for reparation.
In the above method, the unit-conversion switch may be electrically connected in parallel with a remote control device. This remote control device comprises a remote control switch capable of switching the switching elements, such that the device for switching over hub units is switched over either to the first hub unit or to the second hub unit.